On 10/02/2020 14:33, Bert Coules wrote:
"charles" wrote:

Screwfix have Rawlbolts with a fixture size of 75mm in M10. they also do
M12 with a 60mm fixture size.

Thanks, but the baseplate holes are drilled for M6; I'd rather not open
them up as far as M10 or 12.

Bert,

those bolts really need to be screwed into a hole drilled with a 6.5mm
drill (*), and one where there was no lateral wobbling of the drill bit
or you will end up with much larger hole.

The screw bolt needs to cut its own thread into the brick as you
screw it in.

As long as you are drilling into nice strong bricks, or blocks or
concrete then these screws are fine, but remember you must drill a
hole at least half and inch longer than the depth of the screw because
as it cuts its thread, the fragments of brick will be pushed ahead
of the drill bit.

(*) Read the instruction on the box, or check the manufacturers
website.